In any application where fluids are used, sensors are often employed to measure properties of the fluid, such applications including aviation, fluid delivery, heat exchange/refrigeration, semiconductor processing, fluid identification and detection, medical and bio-diagnostics. Quantities measured include temperature, viscosity, density, pressure, flow rate, molecular composition and state of matter. Sensors are transducers, which convert the property being measured into another useful form, often electrical, for recording, observing and controlling. In order to make a useful sensor, the device must respond to a physical input change by producing an output change. The degree to which the output changes with respect to the input change is termed the sensitivity of the sensor.